ABSTRACT
EXPERIMENTAL STUDIES OF THINNING LIQUID FILMS
20.1 Introduction A wide range of techniques have been used to study the properties of liquid films, in particular free films (i.e. gas-liquid-gas systems). There exist a number of excellent reviews on these techniques, including [1, 2]. Free films can be drawn up onto a frame from an aqueous surfactant solution and their thickness observed as a function of time as the liquid drains vertically back into the solution. Interference colors appear when the film is still thick (500 nm) but as it thins down to a thickness well below the wavelength of visible light ( 10-20 nm), the film appears to be black and is called the black film.
